import React, {
  PropsWithChildren,
  ReactNode,
  CSSProperties,
  useMemo,
  useState,
  useRef,
  useEffect,
} from 'react';
import styled, { keyframes } from 'styled-components';
import { Icon } from '../icon';
import { color, typography } from '../shared/styles';
import { darken, rgba, opacify } from 'polished';
import { easing } from '../shared/animation';
import { format } from 'path';

const originPadding = 24; //原始间距

interface DragControlData {
  drag: boolean;
  x: number;
  itemkey: string;
}

interface DragHighlight {
  drag: boolean;
  itemkey: string;
}

interface TreeItemType {
  level: number;
  itemkey: string;
  highlight: DragHighlight;
  borderColor?: string;
}

type TreeGragType = {
  gkey: string,
  backColor?: string,
} & DragControlData;

const TreeGrag = styled.div<TreeGragType>`
  position: absolute;
  width: 100%;
  height: 90%;
  ${(props) => {
    switch (props.x) {
      case 1:
        return `margin-left:${-levelSpace}px ;`;
      case 2:
        return '';
      case 3:
        return `margin-left:${levelSpace}px  ;`;
      default:
        return '';
    }
  }};
  ${(props) => {
    if (props.itemkey === props.gkey) {
      return `background: ${props.backColor};`;
    }
  }}
`;

const TreeItem = styled.div<TreeItemType>`
  padding-left: ${(props) => originPadding * props.level}px;
  padding-top: 2px;
  padding-bottom: 2px;
  display: flex;
  align-items: center;
  position: relative;
  overflow: hidden;
  ${(props) => {
    if (props.highlight.drag && props.highlight.itemkey === props.itemkey) {
      return `border: 1px dashed ${props.borderColor};`;
    } else {
      return '';
    }
  }}
`;

const TreeIcon = styled.span<{ g: itemPropsRequired }>`
  & > svg {
    transition: linear 0.2s;
    height: 10px;
    margin-bottom: 5px;
    ${(props) => {
    if (props.g.children && props.g.children.length !== 0) {
      if (props.g.children[0] && props.g.children[0]['visible']) {
        return 'display:inline-block;transform: rotate(-90deg);';
      } else {
        return 'display:inline-block;';
      }
    } else {
      return 'opacity:0';
    }
  }};
  }
`;

const flatten = function (
  list: Array<itemProps>,
  level = 1,
  parent: itemProps,
  defaultExpand = true
): itemPropsRequired[] {
  let arr: itemPropsRequired[] = []; //收集所有子项
  list.forEach((item) => {
    item.level = level;
    if (item.expand === undefined) {
      item.expand = defaultExpand;
    }
    if (item.visible === undefined) {
      item.visible = true;
    }
    if (!parent.visible || !parent.expand) {
      item.visible = false;
    }
    if (item.key === undefined) {
      item.key = item.value + Math.random();
    }

    item.parent = parent;
    arr.push(item as itemPropsRequired);
    if (item['children']) {
      arr.push(...flatten(item['children'], level + 1, item, defaultExpand));
    }
  });
  return arr;
};

interface itemProps {
  value: string;
  level?: number;
  expand?: boolean;
  visible?: boolean;
  parent?: itemProps;
  children?: Array<itemProps>;
  key?: string;
}

interface itemPropsRequired
  extends Omit<Required<itemProps>, 'children' | 'parent'> {
  children?: itemPropsRequired[];
  parent: itemPropsRequired;
}

const checkParent = function (g: itemPropsRequired) {
  return g.level === 1;
};

const levelSpace = 20; //同级生效间距
///1插上级 2插同级 3插下级 0不插
const switchInsert = function (diff: number, g: itemPropsRequired) {
  if (!isNaN(diff)) {
    const origin = g.level * 10; //目标原本padding
    if (diff < origin) {
      //移动到padding前全部算上级
      if (checkParent(g)) {
        //排除最顶级
        return 2;
      } else {
        return 1;
      }
    } else if (diff < origin + levelSpace) {
      return 2;
    } else {
      return 3;
    }
  } else {
    return 0;
  }
};

const findOrigin = function (key: string, data: itemPropsRequired[]) {
  const res = data.filter((v) => v.key === key);
  if (res.length > 0) {
    return res[0];
  } else {
    return null;
  }
};

const getParent = function (g: itemPropsRequired) {
  if (g.parent && g.parent.parent) {
    return g.parent.parent;
  } else {
    return g.parent;
  }
};

const judgeChildren = function (
  origin: itemPropsRequired,
  target: itemPropsRequired
) {
  let sign = true; //如果有孩子就是false
  const fn = (child: itemPropsRequired) => {
    if (child.children) {
      child.children.forEach((v) => {
        if (v === target) {
          sign = false;
          return;
        }
        fn(v);
      });
    }
  };
  fn(origin);
  return sign;
};

const changeOriginParent = function (origin: itemPropsRequired) {
  const parent = origin.parent;
  if (parent.children) {
    const index = parent.children.indexOf(origin);
    if (index > -1) {
      parent.children.splice(index, 1);
    }
    //下面这个方法会产生bug
    //parent.children = parent.children.filter((v) => v !== origin);
  }
};

const changeTargetParent = function (
  parent: itemPropsRequired,
  origin: itemPropsRequired,
  g: itemPropsRequired
) {
  origin.parent = parent;
  if (parent.children) {
    //判断应该插入父级节点哪里
    if (g.parent.children) {
      const index = g.parent.children.indexOf(g);
      if (index > -1) {
        parent.children.splice(index + 1, 0, origin);
      } else {
        //parent传递g会进来
        parent.children.push(origin);
      }
    } else {
      parent.children.push(origin);
    }
  } else {
    parent.children = [origin];
  }
};

const checkTargetOrigin = function (
  g: itemPropsRequired,
  origin: itemPropsRequired
) {
  return g !== origin;
};

const insertTop = function (
  key: string,
  g: itemPropsRequired,
  data: itemPropsRequired[],
  callback: Function
) {
  const origin = findOrigin(key, data);
  //origin插入target上级
  const parent = getParent(g);
  if (
    g.level !== 1 &&
    origin &&
    checkTargetOrigin(g, origin) &&
    judgeChildren(origin, g)
  ) {
    //修改以前父节点
    changeOriginParent(origin);
    //修改目标父节点的父节点（与父节点同级）
    changeTargetParent(parent, origin, g);
    callback();
  }
};

const insertMiddle = function (
  key: string,
  g: itemPropsRequired,
  data: itemPropsRequired[],
  callback: Function
) {
  const origin = findOrigin(key, data);
  //origin插入target同级
  const parent = g.parent;
  if (
    g.level !== 0 &&
    origin &&
    checkTargetOrigin(g, origin) &&
    judgeChildren(origin, g)
  ) {
    changeOriginParent(origin);
    changeTargetParent(parent, origin, g);
    callback();
  }
};

const insertLower = function (
  key: string,
  g: itemPropsRequired,
  data: itemPropsRequired[],
  callback: Function
) {
  const origin = findOrigin(key, data);
  const parent = g;
  if (origin && checkTargetOrigin(g, origin) && judgeChildren(origin, g)) {
    changeOriginParent(origin);
    changeTargetParent(parent, origin, g);
    callback();
  }
};

export function throttle(fn: Function, delay: number = 300) {
  let flag = true;
  return function (...args: any) {
    if (flag) {
      flag = false;
      fn(...args);
      setTimeout(() => {
        flag = true;
      }, delay);
    }
  };
}

export type TreeProps = {
  /** 数据源*/
  source: itemProps[];
  /** 是否可以拖拽 */
  drag?: boolean;
  /** 高亮边框颜色 */
  borderColor?: string;
  /** 拖拽提示色 */
  backColor?: string;
  /**外层样式*/
  style?: CSSProperties;
  /**外层类名*/
  classname?: string;
};

const changeVisible = (item: itemPropsRequired, callback: Function) => {
  //给点击的children设置visible
  if (item.children) {
    //避免children有显示不一行为
    let visible: boolean;
    const depth = (item: itemPropsRequired[]) => {
      item.forEach((v) => {
        if (visible === undefined) {
          visible = !v.visible;
        }
        v.visible = visible;
        if (v.children) {
          //把孩子全部改掉
          depth(v.children);
        }
      });
    };
    depth(item.children);
    callback(); //改完后更新页面
  }
};

export function Tree(props: TreeProps) {
  const img = new Image();
  img.src = 'https://www.easyicon.net/api/resizeApi.php?id=1200841&size=32';
 
  const { source, backColor, borderColor, drag } = props;

  const root = useMemo(() => {
    return {
      level: 0,
      visible: true,
      expand: true,
      children: source,
      value: 'root',
    };
  }, [source]);
  const [dragUpdate, setDragUpdate] = useState(0);
  const data = useMemo(() => {
    return flatten(root.children, 1, root);
  }, [root, dragUpdate]);
  const [start, setStart] = useState(0);
  const forceUpdate = useState(0)[1];
  const ref = useRef<HTMLDivElement>(null);

  const [highlight, setHighlight] = useState({
    drag: true,
    itemkey: '',
  });

  useEffect(() => {
    if (ref.current) {
      setStart(ref.current.getBoundingClientRect().left); //为了找到起始
    }
  }, []);

  useEffect(() => {
    const handler = () => {
      setDragOver((prev) => ({ ...prev, drag: false }));
      setHighlight({
        drag: false,
        itemkey: '',
      });
    };
    window.addEventListener('dragend', handler);
    return () => {
      window.removeEventListener('dragend', handler);
    };
  }, []);

  const [dragOver, setDragOver] = useState<DragControlData>({
    drag: false,
    x: 0,
    itemkey: '',
  });

  const dragHandler = (
    clientX: number,
    itemkey: string,
    g: itemPropsRequired
  ) => {
    const diff = clientX - start;
    const x = switchInsert(diff, g);
    setDragOver({
      drag: true,
      x,
      itemkey,
    });
  };

  const callback = () => {
    forceUpdate((state) => state + 1);
  };

  const dragCallback = () => {
    setDragUpdate((state) => state + 1);
  };

  return (
    <div ref={ref}>
      {data
        .filter((v) => v.visible === true)
        .map((g) => {
          return (
            <TreeItem
              itemkey={g.key}
              highlight={highlight}
              level={g.level}
              borderColor={borderColor}
              draggable={drag}
              onClick={() => changeVisible(g, callback)}
              key={g.key}
              onDragStart={(e) => {
                e.dataTransfer.setData('endykey', `${g.key}`);
                e.dataTransfer.setDragImage(img, 29, 29);
                setHighlight({
                  drag: true,
                  itemkey: g.key,
                });
              }}
              onDragOver={(e) => {
                e.preventDefault();
                throttle(dragHandler)(e.clientX, g.key, g);
              }}
              onDrop={(e) => {
                const key = e.dataTransfer.getData('endykey');
                const left = e.clientX;
                const diff = left - start; //离顶部差值
                const res = switchInsert(diff, g);
                switch (res) {
                  case 1:
                    insertTop(key, g, data, dragCallback);
                    break;
                  case 2:
                    insertMiddle(key, g, data, dragCallback);
                    break;
                  case 3:
                    insertLower(key, g, data, dragCallback);
                    break;
                  default:
                    break;
                }
              }}
            >
              {dragOver.drag && (
                <TreeGrag
                  gkey={g.key}
                  backColor={backColor}
                  drag={dragOver.drag}
                  x={dragOver.x}
                  itemkey={dragOver.itemkey}
                ></TreeGrag>
              )}
              <TreeIcon g={g}>
                <Icon icon="arrowdown"></Icon>
              </TreeIcon>
              <span>{g.value}</span>
            </TreeItem>
          );
        })}
    </div>
  );
}

Tree.defaultProps = {
  source: [],
  drag: true,
  borderColor: '#53c94fa8',
  backColor: '#00000030',
};
